Re: PCI: bridge window undersized when child bridge windows are larger than their alignment (regression since 3958bf16e2fe, v7.0)

[sashiko-bot@kernel.org]

> Hi,
> 
> On a Mac Pro 7,1 with two Radeon Pro Vega II Duo cards, enabling 32 GB
> Resizable BARs leaves exactly half the GPU dies with no BAR at all. The
> shared root-port prefetchable window is sized as the plain sum of its two
> child bridge windows, but each child secretly requires a 32 GB-aligned
> start, so the window that gets allocated is ~32 GB smaller than the span
> that is actually needed. The second child of each pair loses,
> deterministically.
> 
> There is 1 TiB of free space in the host bridge's _CRS window, so this is
> not address-space exhaustion.
> 
> This is a regression. On the same machine, with the same script
> (resize-amdgpu-bars, https://github.com/exabit-io/resize-amdgpu-bars,
> [ ... ]
>   - lspci -vvnn from the v7.0.12 + patch boot
> 
> 
> #regzbot introduced: 3958bf16e2fe
> 

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260903063124.9316-1-nbritton@exabit.io?part=1